If you wanna make a european tour (but how? long budget?), i'd recommend 3 days in London, 3 in Paris, then 2 in Bruxelles, 2-3 in Amsterdam, 1 in Luxembourg, then towards Italy(Rome, Venise--5days) via Germany or better, Switzerland(2-3 days stop)....if you re still hungry, you can then do the south coast of France (make a stop somewhere like Nice/Monaco/Marseille (i guess the most touristic should be Nice) and then head towards Spain...and there Portugal's just a step away...i know it probably is unrealistic unless you've got one month to travel.